Gage Meghan, Rao Nikhil S, Samidurai Manikandan, Putra Marson, Vasanthi Suraj S, Meyer Christina, Wang Chong, Thippeswamy Thimmasettappa
Neuroscience Interdepartmental Program, Iowa State University, Ames, IA, United States.
Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, United States.
Front Cell Neurosci. 2022 Feb 7;15:798247. doi: 10.3389/fncel.2021.798247. eCollection 2021.
Modeling a real-world scenario of organophosphate nerve agent (OPNA) exposure is challenging. Military personnel are premedicated with pyridostigmine, which led to the development of OPNA models with pyridostigmine/oxime pretreatment to investigate novel therapeutics for acute and chronic effects. However, civilians are not premedicated with pyridostigmine/oxime. Therefore, experimental models without pyridostigmine were developed by other laboratories though often only in males. Following OPNA exposure, prolonged convulsive seizures (CS) or (SE) are concerning. The duration and severity of CS/SE determine the extent of brain injury in survivors even after treating with medical countermeasures (MCM)/antidotes such as atropine, an oxime, and an anticonvulsant such as diazepam/midazolam. In this study, using a large mixed sex cohort of adult male and female rats, without pretreatment, we demonstrate severe SE lasting for >20 min in 82% of the animals in response to soman (GD,132 μg/kg, s.c.). Atropine sulfate (2 mg/kg, i.m.) and HI-6 (125 mg/kg, i.m.) were administered immediately following soman, and midazolam (3 mg/kg, i.m.) 1 h post-exposure. Immediate MCM treatment is impractical in civilian exposure to civilians, but this approach reduces mortality in experimental models. Interestingly, female rats, irrespective of estrous stages, had an average of 44 min CS (stage ≥ 3), while males had an average of 32 min CS during SE, starting from soman exposure to midazolam treatment. However, in telemetry device implanted groups, there were no significant sex differences in SE severity; males had 40 min and females 43 min of continuous CS until midazolam was administered. No animals died prior to midazolam administration and less than 5% died in the first week after soman intoxication. In telemetered animals, there was a direct correlation between EEG changes and behavioral seizures in real-time. In the long-term, convulsive spontaneously recurring seizures (SRS) were observed in 85% of randomly chosen animals. At 4-months post-soman, the brain histology confirmed reactive gliosis and neurodegeneration. The novel findings of this study are that, in non-telemetered animals, the SE severity following soman intoxication was significantly greater in females compared to males and that the estrous cycle did not influence the response.
模拟有机磷酸酯类神经毒剂（OPNA）暴露的真实场景具有挑战性。军事人员会预先服用吡啶斯的明，这促使人们开发出经吡啶斯的明/肟预处理的OPNA模型，以研究针对急性和慢性影响的新型治疗方法。然而，平民不会预先服用吡啶斯的明/肟。因此，其他实验室开发了未用吡啶斯的明的实验模型，但通常仅在雄性动物中进行。OPNA暴露后，长时间的惊厥性癫痫发作（CS）或癫痫持续状态（SE）令人担忧。CS/SE的持续时间和严重程度决定了幸存者脑损伤的程度，即使在使用医疗对策（MCM）/解毒剂（如阿托品、肟）和抗惊厥药（如地西泮/咪达唑仑）治疗后也是如此。在本研究中，我们使用了一大群成年雄性和雌性大鼠的混合性别队列，未进行预处理，结果显示，在给予梭曼（GD，132μg/kg，皮下注射）后，82%的动物出现了持续超过20分钟的严重SE。梭曼给药后立即给予硫酸阿托品（2mg/kg，肌肉注射）和HI-6（125mg/kg，肌肉注射），暴露1小时后给予咪达唑仑（3mg/kg，肌肉注射）。在平民接触中，立即进行MCM治疗不切实际，但这种方法可降低实验模型中的死亡率。有趣的是，从梭曼暴露到咪达唑仑治疗期间，无论处于发情周期的哪个阶段，雌性大鼠的平均CS时间为44分钟（≥3期），而雄性大鼠的平均CS时间为32分钟。然而，在植入遥测设备的组中，SE严重程度没有显著的性别差异；在给予咪达唑仑之前，雄性大鼠有40分钟的持续CS，雌性大鼠有43分钟。在给予咪达唑仑之前没有动物死亡，梭曼中毒后第一周内死亡的动物不到5%。在植入遥测设备的动物中，脑电图变化与实时行为性癫痫发作之间存在直接相关性。从长期来看，在85%的随机选择的动物中观察到惊厥性自发复发性癫痫发作（SRS）。在梭曼中毒后4个月，脑组织学证实有反应性胶质增生和神经退行性变。本研究的新发现是，在未植入遥测设备的动物中，梭曼中毒后的SE严重程度在雌性中明显高于雄性，且发情周期不影响反应。
